Re: Can i assign the device to a group while creating the ob

No, and no, sorry. The group is just another manages object that has 'childAssets', so to add a device to a group you need to add a reference to a device to the group child assests, and this requires a separate request. With 'externalId' at the moment you also need a separate request to 'identity' API, byr we do plan to store those inside the manageded object itself in the future, so it will be possible to assign them upon creation, but it's not available yet.